Variable flow regulator for use with catalytic converters

ABSTRACT

A variable flow regulator assembly comprises a first stationary exhaust pipe, a second stationary exhaust pipe concentrically disposed within the first stationary exhaust pipe, and a movable exhaust pipe concentrically disposed between the first and second stationary exhaust pipes. The first stationary exhaust pipe includes one or more interference tabs concentrically and circumferentially fitted about its interior surface. The movable exhaust pipe includes one or more interference tabs concentrically and circumferentially fitted about its exterior surface. The interference tabs complimentarily interact and restrict the movement of the variable flow regulator so that the flow maldistribution of the exhaust gas stream entering the catalytic converter can be variably controlled.

TECHNICAL FIELD

The disclosure relates to catalytic converters for mobile vehicles and,more particularly, to an apparatus and method for improving catalyticconverter performance.

BACKGROUND

The reduction of emissions from vehicle exhaust systems is a well knownproblem. As the number of vehicles having an internal combustion enginecontinues to increase, the problem is becoming more severe and despitethe introduction of catalytic converter exhaust systems, the exhaustemissions from vehicles fitted with such systems are still relativelyhigh.

In particular exhaust emissions are relatively high during the initialwarm-up phase, also referred to as the “cold start”, of an internalcombustion engine after starting, especially with regard to theemissions of carbon monoxide, oxides of nitrogen and hydrocarbons. Coldstart conditions refer to when the catalytic converter is not operating.For example, this could be on a cold winter day when the temperature is−10° C. or on a summer day when the ambient temperature is 30° C. Thecatalytic converter must be heated to approximately 250° C. before itbecomes operable to convert the combustion by-products of the internalcombustion engine. Normal operating temperature is in the 400° C. to800° C. range. For the internal combustion engine to meet the FederalTest Procedure for the new stringent exhaust requirements, the catalystmust come up to temperature as quickly as possible.

The particularly high exhaust emissions are largely due to the fact thatthe catalytic converter has not reached its so-called “light-off”temperature, at which the catalyst causes the required catalyticreactions to take place. The light-off temperature can be defined as thetemperature at which the catalytic converter reaches 50% conversion.Modern catalyst systems start operating at temperatures of around 200°C. to 300° C.

In order to reduce the quantity of harmful emissions during the initialwarm-up phase, a plurality of different solutions has been proposed,many of these solutions being based on shortening the time taken toreach the light-off temperature by raising the temperature in thecatalyst as fast as possible. During a cold start, this can be achievedby generating increased heat energy into the exhaust system, whichsubsequently causes the catalyst to be rapidly heated.

A previously known arrangement for obtaining this reduction in time forthe light-off temperature to be reached is one comprising anelectrically heated catalyst, which is arranged upstream from the maincatalyst. However, this arrangement implies certain drawbacks. Firstly,the cost for a heatable catalyst substrate is considerable. Furthermore,the consumption of electrical energy is relatively high. An additionalpower supply such as an extra battery may be required in the vehicle.Also, the durability of the electrically heatable catalyst substrate mayconstitute a problem.

Consequently, there exists a need for a catalytic converter that canaccelerate catalyst light-off time without increasing the emissions fromthe vehicle's exhaust system.

SUMMARY

The drawbacks and disadvantages of the prior art are overcome by theexemplary embodiments of the variable flow regulator, catalyticconverter, and method for achieving light-off in a catalytic converter.The variable flow regulator assembly comprises a first exhaust pipehaving at least one interference tab concentrically andcircumferentially disposed on an interior surface of the first exhaustpipe, a second exhaust pipe concentrically disposed within the firstexhaust pipe, and a movable exhaust pipe having at least oneinterference tab concentrically and circumferentially disposed on anexterior surface of the exhaust pipe. An actuation mechanism is incommunication with the first exhaust pipe, the second exhaust pipe andthe movable exhaust pipe. The movable exhaust pipe concentricallydisposed about the second exhaust pipe, and between the first exhaustpipe and the movable exhaust pipe.

The catalytic converter comprises a catalyst substrate comprising acatalyst, a shell having an opening, and the shell is concentricallydisposed around said catalyst substrate, a mat support material disposedbetween the catalyst substrate and the shell, and concentrically aroundthe catalyst substrate, and a variable flow regulator concentricallydisposed within the shell. An end cone assembly is attached to thevariable flow regulator assembly. The variable flow regulator assemblycomprises a first exhaust pipe, a second exhaust pipe concentricallydisposed within the first exhaust pipe, and a movable exhaust pipeconcentrically disposed between the first exhaust pipe and the secondexhaust pipe.

A method for achieving light-off in a catalytic converter comprisesactivating the catalytic converter under cold start conditions. Exhaustgas is introduced into the catalytic converter through a variable flowregulator attached thereto, wherein the variable flow regulatorcomprises a first exhaust pipe having at least one interference tabconcentrically and circumferentially disposed on an interior of thefirst exhaust pipe, a second exhaust pipe concentrically disposed withinthe first exhaust pipe, and a movable exhaust pipe having at least oneinterference tab disposed concentrically and circumferentially on anexterior of said movable exhaust pipe, and disposed concentricallybetween the first exhaust pipe and the second exhaust pipe. The flowmaldistribution is controlled using the variable flow regulator.Light-off is achieved in the catalytic converter.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the figures, which are meant to be exemplary, notlimiting, and wherein like elements are numbered alike in the severalfigures.

FIG. 1 is an exemplary embodiment of a catalytic converter;

FIG. 2 is a cross-sectional view of the catalytic converter of FIG. 1having an exemplary embodiment of a variable flow regulator.

FIG. 3 is an enlarged partial cross-sectional view of the catalyticconverter and variable flow regulator of FIG. 2 at a first position.

FIG. 4 is an enlarged partial cross-sectional view of the catalyticconverter and variable flow regulator of FIG. 2 at a second position.

FIG. 5 is an enlarged partial cross-sectional view of the catalyticconverter and variable flow regulator of FIG. 2 at a third position.

FIG. 6 is a cross-sectional view of an exemplary embodiment of acatalytic converter having an another exemplary embodiment of a variableflow regulator.

FIG. 7 is an enlarged partial cross-sectional view of the variable flowregulator of FIG. 6 at a first position.

FIG. 8 is an enlarged partial cross-sectional view of the variable flowregulator of FIG. 6 rotated clockwise to a second position.

FIG. 9 is an enlarged partial cross-sectional view of the variable flowregulator of FIG. 6 rotated clockwise to a third position.

FIG. 10 is a cross-sectional view of a conventional circular catalyticconverter with an exemplary variable flow regulator assembly depictingthe contours of static pressure of an exhaust gas flow traveling throughthe variable flow regulator positioned as shown in FIGS. 3 and 7.

FIG. 11 is a cross-sectional view of a conventional circular catalyticconverter without an exemplary variable flow regulator depicting thecontours of static pressure of an exhaust gas flow traveling through thecatalytic converter.

FIG. 12 is a cross-sectional view of a conventional oval shapedcatalytic converter with an exemplary variable flow regulator assemblydepicting the contours of static pressure of an exhaust gas flowtraveling through the variable flow regulator positioned as shown inFIGS. 3 and 7.

FIG. 13 is a cross-sectional view of a conventional oval shapedcatalytic converter without an exemplary variable flow regular depictingthe contours of static pressure of an exhaust gas flow traveling throughthe catalytic converter.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Under cold start conditions, maldistribution, that is an unsatisfactorydistribution of exhaust elements, is high and the thermal content of theexhaust gas stream is focused upon a small thermal mass. Themaldistribution can preferably be variably controlled using a variableflow regulator, as described herein, so that the initial highmaldistribution is concentrated directly into the catalyst substrate. Asa result the environmentally unfriendly elements of the exhaust gas arecatalyzed more efficiently, and the catalytic converter reacheslight-off more quickly.

In addition, as a conventional catalytic converter works to achievelight-off, a back pressure builds in the engine combustion chamber. Whenthe conventional catalytic converter achieves light-off, the backpressure is suddenly reduced, and often times, to quickly for the engineto adjust the fuel to oxygen ratio, which correspondingly reduces theengine's performance i.e., reduced horsepower. The variable flowregulator described herein prevents the typical pressure drop andimproves the engine's overall performance.

A catalytic converter having a variable flow regulator comprises acatalyst substrate comprising a catalyst. The catalyst substrate isdisposed concentrically within a shell having an opening, and a matsupport material is disposed concentrically between the catalystsubstrate and shell, and around the catalyst substrate. The variableflow regulator is disposed within the opening at one end and securedwithin the shell and an end cone assembly, exhaust manifold cover,exhaust pipe, connecting pipe, or other exhaust system component, andthe like. The shell is fitted to an end cone assembly, end plate, andthe like, at the opposite end. The exhaust system component housing thevariable flow regulator is attached to another exhaust system componentsuch as an exhaust pipe, a coupling apparatus, a connecting pipe, anexhaust manifold assembly, combinations comprising at least one of theforegoing, and the like.

One exemplary embodiment of a variable flow regulator assembly comprisesa first stationary exhaust pipe having one or more interference tabscircumferentially fitted about its interior surface, a second stationaryexhaust pipe concentrically disposed within the first stationary exhaustpipe, and a movable exhaust pipe concentrically disposed between theexterior and interior exhaust pipes, and having one or more interferencetabs concentrically and circumferentially fitted about its exteriorsurface. The movable exhaust pipe telescopically extends and retractsfrom a first position to a second position, and to a third position, orback to a first position, along the length of the second stationaryexhaust pipe, and between the first and second stationary exhaust pipes,so that the exhaust gas flow can be variably controlled. Theinterference tabs of the first and movable exhaust pipes interact torestrict the movement of the movable exhaust pipe

Another exemplary embodiment of a variable flow regulator assemblycomprises a first stationary exhaust pipe, a second stationary exhaustpipe concentrically disposed within the first stationary exhaust pipe,and a movable exhaust pipe concentrically disposed between the first andsecond stationary exhaust pipes. In this particular embodiment, themovable exhaust pipe rotates about the second stationary exhaust pipe tovariably control the flow maldistribution of environmentally unfriendlyexhaust gas elements into the catalytic converter. Both the movableexhaust pipe and second stationary exhaust pipe include a plurality ofconcentrical and circumferential slots disposed about an end or outletof both the second and movable exhaust pipes. As the movable exhaustpipe rotates about the second stationary exhaust pipe from a firstposition to a second position, and to a third position, or back to afirst position, both sets of slots interact to variably control the flowof the exhaust gas stream upon entering the catalytic converter. Thefirst stationary exhaust pipe includes one or more interference tabscircumferentially and concentrically fitted about its interior surface.The movable exhaust pipe also includes one or more interference tabscircumferentially and concentrically fitted about its exterior surface.The interference tabs of the first and movable exhaust pipes engage andinteract to restrict the rotational movement of the variable flowregulator.

A catalytic converter 10 comprises at least one catalyst substrate 12.The catalyst substrate 12 can comprise any material designed for use ina spark ignition or diesel engine environment, and have the followingcharacteristics: (1) capable of operating at temperatures up to about1,000° C., (2) capable of withstanding exposure to hydrocarbons,nitrogen oxides, carbon monoxide, carbon dioxide, and/or sulfur; and (3)have sufficient surface area and structural integrity to support thedesired catalyst. Some possible materials include cordierite, siliconcarbide, metallic foils, alumina sponges, porous glasses, and the like,and mixtures comprising at least one of the foregoing. Some ceramicmaterials include “HONEY CERAM”, commercially available from NGK-Locke,Inc, Southfield, Mich., and “CELCOR”, commercially available fromCorning, Inc., Corning, N.Y.

Although the catalyst substrate 12 can have any size or geometry, thesize and geometry are preferably chosen to optimize the surface area inthe given converter design parameters. Typically, the catalyst substrate12 has a honeycomb geometry, with the combs being any multi-sided orrounded shape, with substantially square, hexagonal, octagonal orsimilar geometries preferred due to ease of manufacturing and increasedsurface area.

Disposed on and/or throughout the catalyst substrate 12 is a catalystfor converting exhaust gases to acceptable emissions levels as is knownin the art. The catalyst may comprise one or more catalyst materialsthat are wash coated, imbibed, impregnated, physisorbed, chemisorbed,precipitated, or otherwise applied to the catalyst substrate. Possiblecatalyst materials include noble metals, such as platinum, palladium,rhodium, iridium, osmium and ruthenium; other metals, such as tantalum,zirconium, yttrium, cerium, nickel, copper and the like; metal oxides;and mixtures comprising of at least one of the foregoing, and otherconventional catalysts. The catalyst can optionally include a base metaloxide for the reduction of nitrogen oxides.

Located in between the catalyst substrate 12 and a catalytic convertershell 16 is a mat support material 14 that insulates the shell 16 fromboth high exhaust gas temperatures and the exothermic catalytic reactionoccurring within the catalyst substrate 12. The mat support material 14,which enhances the structural integrity of the catalyst substrate 12 byapplying compressive radial forces about it, reducing its axialmovement, and retaining it in place, is concentrically disposed aroundthe catalyst substrate 12 to form a mat support material/catalystsubstrate subassembly. The mat support material 14 can either be asimple non-intumescent material, or an intumescent material, e.g., onewhich contains a vermiculite component that expands with heating tomaintain firm uniform compression when the shell expands outward fromthe catalyst substrate, as well as materials which include a combinationof both. Typical non-intumescent materials include ceramic materials,and other conventional materials such as an organic binder and the like,or combinations comprising at least one of the foregoing, such as thosesold under the trademarks “NEXTEL” and “SAFFIL” by the “3M” Company,Minneapolis, Minn., or those sold under the trademark, “FIBERFRAX” and“CC-MAX” by the Unifrax Co., Niagara Falls, N.Y., and the like.Intumescent materials, which include ceramic materials, vermiculite, orcombinations comprising at least one of the foregoing, may include otherconventional materials such as organic binders and the like. Examples ofintumescent materials include those sold under the trademark “INTERAM”by the “3M” Company, Minneapolis, Minn., as well as those intumescentswhich are also sold under the aforementioned “FIBERFRAX” trademark, aswell as combinations thereof and others.

The mat support material/catalyst substrate subassembly isconcentrically disposed within the shell 16. The shell 16 includes atleast one opening 18 for receiving the mat support material/catalystsubstrate subassembly. The choice of material for the shell 16 dependsupon the type of exhaust gas, the maximum temperature reached by thecatalyst substrate 12, the maximum temperature of the exhaust gasstream, and the like. Suitable materials for the shell 16 can compriseany material that is capable of resisting under-car salt, temperatureand corrosion. Typically, ferrous material, and the like, is employedsuch as ferritic stainless steels. Some ferritic stainless steelsinclude grades from the 400—Series such as SS-409, SS-439, and SS-441,with grade SS-409 generally preferred. More specifically, SS-409possesses a thermal coefficient of expansion of about 17.3×10⁻⁶/°C.Based upon aΔT of about 370° C., the SS-409 stainless steel compositionexpands about 0.006 mm. When utilized for the exhaust pipes in thepresent application, the circumference of an SS-409 exhaust pipe, havinga diameter of approximately 0.75 mm, expands approximately 1.5 mm, whichwill not interfere with the movement of the variable flow regulator orthe interaction of the interference tabs.

FIG. 1 illustrates an exemplary embodiment of the shell 16 of theinstant application. The shell 16 can comprise a first end 20, a secondend 22, and a containment area 24. An outer end cone 26 can be fitted toat least one end 20 or 22. Containment area 24 can be sized, such as,e.g. using a draw ring or other conventional means, and reduced indiameter to form a narrow cylindrical area 28 near the first end 20,where the variable flow regulator assembly can be mounted. At least onecatalyst substrate 12 can preferably be disposed within the containmentarea 24, and near the cylindrical area 28, so that the variable flowregulator assembly can direct the exhaust gas stream into the center ofthe catalyst substrate 12.

Typically, the mat support material/substrate subassembly can beinserted into the shell 16 using a variety of methods. In the instantapplication, the subassembly can be placed in a stuffing cone, forexample. The stuffing cone is a device that compresses the mat supportmaterial 14 concentrically about the catalyst substrate 12 using aramming component. The ramming component stuffs the compressed matsupport material/catalyst substrate subassembly into the shell 16without peeling the mat support material 14 away from the catalystsubstrate 12. The shell 16 can be compressively closed upon the matsupport material/catalyst substrate subassembly by exerting asubstantially uniform compressive stress, and complete the assembly ofthe catalytic converter 10.

In the alternative, a compressive sizing operation can be employed whenthe mat support material/catalyst substrate subassembly is disposedconcentrically within the shell 16. The shell 16 can be compressivelysized to achieve the desired mat pressure of the mat support material 14to be exerted upon the catalyst substrate 12. Once the mat supportmaterial/catalyst substrate subassembly is disposed within the shell 16,an outer end cone 26 configured to receive a variable flow regulator canbe attached to the shell 16 at opening 18 to provide a gas tight seal.The outer end cone 26 and variable flow regulator can attach to anexhaust system component such as an exhaust pipe, a connecting pipe, anexhaust manifold assembly, a coupling apparatus, combinations comprisingat least one of the foregoing, other exhaust system components, and thelike.

FIGS. 2-5 depict an exemplary embodiment of a catalytic converter 10fitted with an exemplary embodiment of the variable flow regulatorassembly. A first exemplary embodiment of a variable flow regulatorassembly comprises a first stationary exhaust pipe 32, a secondstationary exhaust pipe 34 concentrically disposed within the firststationary exhaust pipe 32, and a movable exhaust pipe 36 concentricallydisposed between the first and second stationary exhaust pipes 32, 34.One or more interference tabs 38 are concentrically andcircumferentially fitted about the interior surface of the firststationary exhaust pipe 32. In addition, one or more interference tabs40 are concentrically and circumferentially fitted about the exteriorsurface of the movable exhaust pipe 36.

The interference tabs 38 of the first stationary exhaust pipe 32preferably compliment the interference tabs 40 of the movable exhaustpipe 36. The interference tabs include a structural feature such as ajoint configuration, tongue and groove, or one or more members thatoverlap, snap, engage, or interlock, or a device such as a magnetic orelectronic locking mechanism for holding interference tabs 38 and 40 ina complimentary engagement. Under cold start conditions, the movableexhaust pipe 36 is preferably positioned at a resting position, such as,e.g., resting position A (See FIG. 3). At resting position A the movableexhaust pipe 36 is fully extended such that an outlet 37 of the movableexhaust pipe 36 can abut the catalyst substrate 12 or be placed adistance “d” from the catalyst substrate 12, and the interference tabs38, 40 are engaged. By minimizing the distance between the intake areaof the catalyst substrate 12 and the movable exhaust pipe 36, the highmaldistribution can rapidly feed directly into the catalyst substrate12. The catalyst substrate 12 can immediately begin catalyzing theexhaust elements, which causes the temperature of the catalyst substrate12 to quickly rise from its initial cold start temperature.

As the catalytic converter 10 warms and light-off is achieved, themovable exhaust pipe 36 is gradually retracted in a linear motion to asecond position B, located anywhere along the path followed by themovable exhaust pipe 36 until reaching a resting position, such as,e.g., resting position C (See FIGS. 3-5). At resting position C, theoutlet 37 of the movable exhaust pipe 36 substantially aligns with anoutlet 35 of the second stationary exhaust pipe 34. The maldistributionand back pressure gradually decrease without detrimentally impacting theengine's performance, i.e., a decrease in horsepower or fuel efficiency.The variable flow regulator's movement is controlled by the enginecontrol module. In the exemplary embodiment described herein, the enginecontrol module controls the variable flow regulator's movement, and candetermine when to adjust the movable exhaust pipe 36 in at least one ofthe two ways.

First, the engine control module can measure the manifold intakepressure to determine the engine load, while also monitoring the amountof time elapsed from starting the engine. The engine control module cancalculate the conversion exotherm, or heat generated by the catalyticconverter, and the back pressure in the combustion chamber based uponthe aforementioned measurements. As the conversion exotherm increases,the entire exhaust system warms up and achieves thermal inertia, whichovercomes the thermal mass of the system, or the overall temperature theexhaust system must reach to function efficiently. At this point, thecatalytic converter achieves light-off, which is electronically sensedby the engine control module.

Second, the engine control module can monitor the oxygen content of theexhaust gas stream as it passes through the catalytic converter. Oxygensensors can be mounted before and after the catalytic converter. As theexhaust gas stream flows through the catalytic converter, the firstoxygen sensor measures the oxygen content prior to being catalyticallytreated. After passing through the catalytic converter, the oxygencontent of the exhaust gas is measured a second time. The engine controlmodule compares the measurements and determines whether the catalyticconverter achieved light-off. Once the engine control moduleelectronically senses that light-off has occurred, the engine controlmodule adjusts the movable exhaust pipe by gradually retracting the pipefrom position A to position B (See FIGS. 3-4).

As the catalytic converter achieves light-off, pressure builds in theengine combustion chamber. The gradual retraction of the movable exhaustpipe 36 from position A to position B, however, causes the pressure inthe engine combustion chamber to gradually reduce. At the same time theexhaust gas stream flow becomes less restricted, which decreases andimproves the flow maldistribution. The engine control module can monitorthe pressure drop while continuing to electronically adjust the movableexhaust pipe from position B to position C (See FIGS. 4-5). Eventually,the engine control module and variable flow regulator will lower thepressure to a steady state operating level without experiencing a lossin horsepower or fuel efficiency.

The variable flow regulator can be extended and retracted using amechanical or electrical actuation mechanism (not shown), remotely ormechanically operated, such as the type disclosed in U.S. Pat. No.6,101,889 to Laskey, and incorporated herein by reference, and otherdevices designed to actuate or impart movement to a component in alinear direction. Laskey discloses a ball screw and nut linear actuatorassembly. The ball screw and nut linear actuator has a motor and a ballnut and screw assembly in side-by-side disposition. A plurality ofgearing connects with the motor shaft to drive the screw. A housing forthe gearing and ball nut and screw assembly includes an elongate housingtube within which the screw assembly is housed. The nut incorporates anextension sleeve assembly for extending movement out of the housingtube, which anchors the screw against axial movement while journaling itfor rotation. A pin and axial track connection between the extensionsleeve assembly and the housing tube guides the extension sleeveassembly in axial movement and prevents relative rotation of the housingtube and sleeve assembly. The ball screw and nut linear actuatorassembly can be mounted within the first exhaust pipe 32, situatedbehind the third or moveable exhaust pipe 36, and between the firstexhaust pipe 32 and second exhaust pipe 34. Alternatively, the actuatorassembly can be encased in a housing and mounted as described, ormounted externally to the first exhaust pipe 32 in a sealed housingassembly to prevent leakage of exhaust gas from the exhaust system. Theengine control module signals the mechanical actuation mechanism toextend and retract the third exhaust pipe 36, as the engine controlmodule senses the catalytic converter approaching and achievinglight-off.

The flow maldistribution and pressure of the exhaust gas stream can alsobe controlled in a variably uniform manner using another exemplaryembodiment of a variable flow regulator configuration. Referring now toFIGS. 6-9, another exemplary embodiment of the catalytic converter 10connected to a variable flow regulator assembly is depicted. Thevariable flow regulator assembly comprises a first stationary exhaustpipe 32′, a second stationary exhaust pipe 34′ concentrically disposedwithin the first stationary exhaust pipe 32′, and a movable exhaust pipe36′ concentrically disposed between the first and second stationaryexhaust pipes. The second stationary exhaust pipe 34′ includes aplurality of slots 42 concentrically and circumferentially located aboutan outlet 44 of second stationary exhaust pipe 34′. One or moreinterference tabs 38′ are concentrically and circumferentially fittedabout the exterior surface of the second pipe 34′. The movable exhaustpipe 36′ also includes a plurality of slots 42′ concentrically andcircumferentially located about an outlet 44′. In addition one or moreinterference tabs 40′ are also concentrically and circumferentiallyfitted about the interior surface of the movable exhaust pipe 36′. Theinterference tabs 38′, 40′ preferably have the same features, andvariations, as the aforementioned interference tabs 38, 40 of theprevious exemplary embodiment. Interference tabs 38′, 40′ preferablyengage one another to restrict the rotational movement of the movableexhaust pipe 36′ about the second stationary exhaust pipe 34′. Themovable exhaust pipe 36′ rotates about the second stationary exhaustpipe 34′ as an exhaust gas stream flows through the second stationaryexhaust pipe 34′ and into the catalytic converter 10′.

The rotational movement of this exemplary embodiment of the variableflow regulator is also controlled by the engine control module. Theengine control module can determine whether to electronically adjust thevariable flow regulator based upon the aforementioned methods discussedin the previous embodiment. When the engine control module determinesthat the catalytic converter has achieved light-off, the engine controlmodule electronically adjusts the movable exhaust pipe 36′ by graduallyrotating it. The movable exhaust pipe 36′ is preferably situated atposition A under cold start conditions. At position A the slots 42 and42′ are preferably restricted or closed, and the interference tabs 38′,40′ are engaged (See FIG. 7). Once light-off is achieved, the movableexhaust pipe 36′ can gradually rotate in a clockwise direction of arrow46 or counter-clockwise direction of arrow 48 to a position B (See FIG.8). Position B can be any position where the slots 42 and 42′ begin tooverlap and create several additional outlets for the exhaust gas streamto flow through. Meanwhile, the engine control module continuouslymonitors the pressure in the engine combustion chamber and graduallyrotates the movable exhaust pipe 36′ from position B to position C (SeeFIGS. 8-9). At position C the slots overlap each other and effectivelycreate an outlet located approximately several inches before theoriginal outlet of both the second stationary and movable exhaust pipes34′ and 36′ (See FIG. 9). The thermal mass of the exhaust systemachieves the operating temperature such that the catalytic reactionefficiently catalyzes the exhaust stream and lowers the flowmaldistribution.

At that point, both sets of interference tabs 38′, 40′ engage each otherto restrict the rotational movement of the movable exhaust pipe 36′.Again, the engine control module will electronically adjust the movableexhaust pipe 36′ to position C so that the pressure in the enginecombustion chamber achieves a steady state operating level withoutexperiencing a loss in horsepower or fuel efficiency. The engine controlmodule can then adjust and return the movable exhaust pipe 36′ toposition A when the vehicle shuts off.

The variable flow regulator can be rotated clockwise andcounter-clockwise using a mechanical, electrical, or electromagneticactuation mechanism (not shown), remotely or mechanically operated, thatcan impart intermittent or full rotational movement in either direction.Such mechanical, electrical or electromagnetic mechanisms can comprise aball screw apparatus, which rather than translating the rotationalmovement into linear actuation, that is modified to replace the typicalaxle or screw with a linkage connected to the third exhaust pipe of thevariable flow regulator assembly.

Another mechanical, electrical, or electromagnetic mechanism cancomprise configuring the exterior of the third exhaust pipe with aconcentrically disposed rotatable groove or plurality of grooves able toreceive at least one ball bearing. A second concentrically disposedrotatable groove or plurality of grooves able to receive at least oneball bearing is placed on the interior of the first exhaust pipe, andparallel to the groove on the third exhaust pipe. The groove of thefirst exhaust pipe can be mechanically, electrically, orelectromagnetically actuated so that it rotates about the interior ofthe first exhaust pipe in either a clockwise or counterclockwise motion.The clockwise or counterclockwise motion is then imparted to the ballbearing(s). The ball bearing(s) in turn impart a counter directionalforce to the third exhaust pipe through the groove, such that the thirdexhaust pipe rotates in a counterclockwise direction when acted upon bya ball bearing moving in a clockwise direction, and likewise, rotates ina clockwise direction when acted upon by a ball bearing moving in acounterclockwise direction.

Yet another mechanical or electrical mechanism can comprise a modifiedmulti-functional apparatus employing an intermittent motor mechanismsuch as the apparatus disclosed in WO/96,33891, U.S. Pat. No. 6,075,298,and U.S. Pat. No. 6,107,759. Multi-functional apparatus for vehiclestypically operate several functions, such as a window wiper mechanism,front and rear window locks, and lift gate lock mechanisms, usingintermittent rotational motion to move, for example, a window wiper sideto side across a windshield. That same type of intermittent motormechanism can be mounted within the exemplary variable flow regulator,and modified for remote actuation of the variable flow regulator alone,according to signals received from the engine control module.

For example, the output pinion of the rotatable member in FIG. 1a ofU.S. Pat. No. 6,107,759, incorporated herein by reference, can beimplemented with the third exhaust pipe, such that the third exhaustpipe can be equipped with a worm gear groove or plurality of worm geargrooves concentrically disposed about a portion of its exterior, andsuch grooves are placed in physical contact and communication with anoutput pinion for interaction with the rotatable member. As therotatable member imparts a rotational movement to the output pinion, thethird exhaust pipe rotates about the first exhaust pipe. The variableflow regulator can then operate independently to quickly achieve a quickcatalyst light-off without the drawbacks associated with a strictlymulti-functional motor mechanism, i.e., typically, when one function,such as a door lock, is impaired, then the remaining functions becomeimpaired as well. The intermittent motor mechanism can be mounted withinthe first exhaust pipe 32′, situated between the first exhaust pipe 32′and third exhaust pipe 36′, and impart a rotational movement to thethird exhaust pipe 36′ in either a clockwise or counterclockwisedirection about the first exhaust pipe 32′, according to the enginecontrol module. Alternatively, the actuator assembly can be encased in ahousing and mounted as described, or mounted externally to the firstexhaust pipe 32 in a sealed housing assembly to prevent leakage ofexhaust gas from the exhaust system.

The exemplary variable flow regulator, when coupled to either aconventional circular or oval shaped catalytic converter, enhances theperformance of the catalytic converter by increasing the pressure atwhich the exhaust gas travels through the converter, as well as the flowmaldistribution, and thus quickening the light-off of the catalyticconverter. As shown in FIG. 10, the exhaust gas flow is concentratedthrough the center of the catalyst substrate at a higher pressure, asillustrated by the pressure waves moving from left to right along the xaxis, than a catalytic converter operating without a variable flowregulator assembly. As a result, the catalyst substrate's catalyticreaction immediately occurs, thus causing the temperature to increasequickly, and accelerating the light-off. In contrast, FIG. 11illustrates a conventional catalytic converter operating without avariable flow regulator assembly. The exhaust gas passes through thecatalyst substrate at a lower pressure, which does not subsequentlyaccelerate the catalytic reaction or increase the temperature of thecatalyst substrate. In an experimental simulation, both variable flowregulator embodiments directed the exhaust gas flow into a circularcatalytic converter at a pressure gradient ΔP of about 6080 pascals(Pa), in comparison to the conventional circular catalytic converter ofFIG. 11, which only maintained an exhaust gas flow pressure gradient ΔPof about 2816 pascals.

Likewise, in a similar experimental simulation employing an oval shapedcatalytic converter in FIGS. 12 and 13, the variable flow regulatordirected the exhaust gas flow into the catalytic converter at a pressuregradient ΔP of about 6029 pascals, in comparison to the conventionaloval shaped catalytic converter of FIG. 13, which only maintained anexhaust gas flow pressure gradient ΔP of about 2919 pascals. Asdemonstrated by the pressure waves in FIG. 12, the variable flowregulator concentrated the flow through the catalyst substrate, whichaccelerated the catalyst reaction occurring within and quickened thelight-off. In contrast, the conventional catalytic converter could notconcentrate the exhaust gas stream through the center of the catalystsubstrate and generate the same benefits as the variable flow regulator,and the pressure gradients reflect this difference.

The variable flow regulator disclosed herein eliminates having to createa richer air/fuel mixture during the initial warming phase to achieve aquicker catalytic converter light-off time. A richer air/fuel mixturecan be used to create a greater exothermic oxidation of exhaust elementswithin the combustion chamber of the vehicle's engine. The exhaust gasstream can increase in temperature and, likewise, cause the catalyticconverter to rapidly increase in temperature and facilitate a quickerlight-off time. The great disadvantage to enriching the air/fuel mixtureis that the vehicle's engine performance is compromised. Theconventional arrangement of exhaust engine components cannot beeffectively tuned for optimum engine power and engine torque. Withregard to the tuning of an engine, the design of the engine outletsshould always be considered, so as to provide an optimum volumetricefficiency of the engine. The geometry of conventional exhaust manifoldsdo not allow any such tuning, which is essential if the engine'sperformance is to be optimized. The variable flow regulator describedherein can optimize catalytic converter light-off without compromisingboth fuel efficiency and engine performance by directing andconcentrating the exhaust gas flow through the center of the catalystsubstrate.

While preferred embodiments have been shown and described, variousmodifications and substitutions may be made thereto without departingfrom the spirit and scope of the invention. Accordingly, it is to beunderstood that the present invention has been described by way ofillustration and not limitation.

1. A catalytic converter comprising: a catalyst substrate comprising acatalyst; a shell having an opening, and said shell concentricallydisposed around said catalyst substrate; a mat support material disposedbetween said catalyst substrate and said shell, and concentricallyaround said catalyst substrate; a variable flow regulator concentricallydisposed within said shell; an end cone assembly attached to said shellat the opening and 1 said variable flow regulator assembly; and saidvariable flow regulator assembly comprises a first exhaust pipe, asecond exhaust pipe concentrically disposed within said first exhaustpipe, and a movable exhaust pipe concentrically disposed between saidfirst exhaust pipe and said second exhaust pipe.
 2. The catalyticconverter recited in claim 1, wherein said first exhaust pipe comprisesone or more interference tabs fitted concentrically andcircumferentially about an interior surface of said first exhaust pipe.3. The catalytic converter recited in claim 2, wherein said movableexhaust pipe includes one or more interference tabs fittedconcentrically and circumferentially about an exterior surface of saidmovable exhaust pipe.
 4. The catalytic converter recited in claim 3,wherein said interference tabs of said movable exhaust pipe and saidinterference tabs of said first exhaust pipe are configured to interactand restrict the movement of said variable flow regulator.
 5. Thecatalytic converter recited in claim 1, wherein said movable exhaustpipe is configured to move in a linear direction along said secondexhaust pipe, and between said first exhaust pipe and said secondexhaust pipe, from a first position to a second position, and to a thirdposition or to said first position, and from said third position to saidfirst position.
 6. The catalytic converter recited in claim 1, whereinsaid movable exhaust pipe is configured to rotate in a clockwisedirection and a counterclockwise direction about said second exhaustpipe, and between said first exhaust pipe and said second exhaust pipe,from a first position to a second position, and to a third position orto said first position, and from said third position to said firstposition.
 7. The catalytic converter recited in claim 6, wherein saidmovable exhaust pipe further comprises a plurality of slotsconcentrically and circumferentially disposed about an outlet of saidmovable exhaust pipe, and said second exhaust pipe further comprises aplurality of slots concentrically and circumferentially disposed aboutan outlet of said second exhaust pipe.
 8. The catalytic converterrecited in claim 1, wherein said shell further comprises a first end, asecond end, and a containment area having a cylindrically shaped portionapproximate to said first end.
 9. A method for manufacturing a catalyticconverter, comprising: forming a catalyst substrate comprising acatalyst; disposing said catalyst substrate concentrically within ashell having an opening; disposing concentrically a mat support materialin between said catalyst substrate and said shell, and around saidcatalyst substrate; disposing concentrically a variable flow regulatorwithin said shell, wherein said variable flow regulator assemblycomprises a first exhaust pipe, a second exhaust pipe concentricallydisposed within said first exhaust pipe, and a movable exhaust pipeconcentrically disposed between said first exhaust pipe and said secondexhaust pipe.
 10. The method recited in claim 9, further comprisingattaching said variable flow regulator to an endcone.
 11. The methodrecited in claim 10, further comprising attaching said endcone to anexhaust system component selected from the group consisting of anexhaust pipe, a coupling apparatus, a connecting pipe, an exhaustmanifold assembly, and combinations comprising at least one of theforegoing.